1. Field of the Invention
This invention relates to a strapping machine, particularly to one possible to automatically adjust the strap tension for various sizes of an object to be strapped.
2. Description of the Prior Art
A conventional strapping machine shown in FIG. 1, includes an arch frame 11, an supersonic sensor 12 on the arch frame 11, and a detecting table 13 for placing an object 14 to be strapped with a height (H), a signal processor receiving signals from the sensor 12, and a controller receiving a signal from the signal processor so as to give a proper strap tension to the strap 15 for strapping the object with various heights (H).
The conventional strapping machine 10 can adjust the strap tension for a strap 15 for binding an object with a different height (H) by means of the supersonic sensor 12, with the height functioning as a critical condition for adjusting. However, an object to be strapped may have different width to change the volume of an object to be strapped with the same height, but the supersonic sensor only detects the height, but not the width so the real volume may not be detected out, impossible to accurately control the strap tension for the object to be strapped. Therefore, the strap 15 may have too loose or too tight tension for the object.